When a toll road is included in a guide route, an in-vehicle navigation apparatus calculates a toll from an entrance interchange via which the vehicle has entered the toll road to an exit interchange, via which the vehicle is assumed to exit the toll road. The calculated toll is notified to a user (see Patent document 1).
An in-vehicle navigation apparatus has a function to re-retrieve a guide route in the following cases: (1) when the present position of the vehicle changes without continuity while the guide route is provided (i.e., when a present position as the result of a map matching process changes significantly from a present position detected by a position detection unit), (2) when the user changes the destination, (3) when the user deviates from the guide route, and (4) when the guide route is obliged to change based on the congestion information from an outside.
The re-retrieval of the guide route is performed from the present position to the destination. If the re-retrieval of the guide route is executed after entering a toll road, data on the entrance IC previously passed through disappears. A toll of the toll road may be unable to be correctly calculated.
In another navigation apparatus, whether a vehicle reaches an entrance interchange is determined independently of the navigation apparatus. The data on the determined entrance IC is stored in memory. Even if a re-retrieval of the guide route is executed, a correct toll up to an exit interchange is calculated with the stored exit interchange referred to. The calculated toll is notified to a user (see Patent document 2).                Patent document 1: JP-H9-269236 A        Patent document 2: JP-H11-295094 A        
In the navigation apparatus in Patent document 2, the vehicle having reached an entrance interchange is determined when (i) the present position detected by a position detection unit is near the position of an entrance interchange on map data, and at the same time (ii) a vehicle's window opens and closes or the vehicle stops.
The detected vehicle present position may deviate from an actual present position because of detection error of the position detection unit. To anticipate the above, the vehicle present position on the map data is periodically adjusted (i.e., map matching process is performed) to keep the consistency with the map data in Patent document 2. In the map matching process, the present position is adjusted to the position on the road (link) nearest to the vehicle present position on the map data.
For instance, in an area where roads entering a toll road are close to each other, the map matching process does not function properly, but the following may occur.
FIG. 11 illustrates that Roads 111 and 112 connected with Main line 110 of Toll road 119 exist close to each other.
Arrow 113 (broken line) indicates an actual travel locus of the vehicle. The vehicle enters Main line 110 of Toll road 119 via Entrance interchange 111. It is assumed that when the vehicle passes through Entrance interchange 111, the above position detection error arises.
Because of the detection error, the vehicle present position may deviate greatly from Entrance road 111 to be closer to Entrance road 112 having Entrance interchange 112 on the map data. In this case, the vehicle is regarded as being located in Entrance road 112 as a result of the map matching process. The vehicle is therefore incorrectly determined to have entered Toll road 119 via Entrance interchange 112. Hereinafter, it is called “location gap” that the vehicle present position designated on the map deviates from the actual present position because of the detection error. That is, the vehicle present position changes without continuity (refer to above (1)).
In Patent document 2, when the above location gap occurs, Entrance interchange 112 is stored as an entrance interchange, which the vehicle has passed through, and a re-retrieval of the guide route is performed from the present position (i.e., entrance interchange 112). That is, because of the location gap, the travel locus is regarded as Arrow 114 instead of Arrow 113 of the actual travel locus of the vehicle. For example, the vehicle is going to exit Main line 110 of Toll road 119 via Exit interchange 115 of Exit road 115. The toll is calculated from Entrance interchange 112 to Exit interchange 115, instead of being calculated from Entrance interchange 111 to Exit interchange 115. Thus, the incorrect toll may be notified to the user.